What is the treatment for acute renal vein thrombosis?

Treatment of Acute Renal Vein Thrombosis

Initiate immediate anticoagulation with intravenous unfractionated heparin (UFH) as first-line therapy, with catheter-directed thrombectomy/thrombolysis reserved for patients with deteriorating renal function or complete renal vein occlusion threatening kidney viability.

Initial Anticoagulation Strategy

Standard Anticoagulation Approach

• Begin UFH intravenously with an 80 U/kg bolus followed by 18 U/kg/hour continuous infusion, targeting an aPTT of 1.5-2.5 times baseline 1
• Alternative dosing is 5000 IU bolus followed by approximately 30,000 IU over 24 hours, adjusted to maintain therapeutic aPTT 1
• Low-molecular-weight heparin (LMWH) is an acceptable alternative: enoxaparin 1 mg/kg subcutaneously twice daily or dalteparin 200 U/kg once daily for patients with creatinine clearance ≥30 mL/min 1
• Fondaparinux (weight-based: 5 mg for <50 kg, 7.5 mg for 50-100 kg, 10 mg for >100 kg subcutaneously once daily) can also be used 1

Critical Renal Function Considerations

• In patients with severe renal impairment (creatinine clearance <25-30 mL/min), UFH is strongly preferred over LMWH due to accumulation risk and increased bleeding with LMWH 1
• UFH undergoes hepatic metabolism rather than renal clearance, eliminating accumulation concerns 2
• If LMWH must be used in renal impairment, anti-Xa monitoring is mandatory 1

Endovascular Intervention Indications

When to Consider Catheter-Directed Therapy

Catheter-directed thrombectomy with or without thrombolysis should be considered for:

• Complete renal vein occlusion with rapidly deteriorating renal function (rising creatinine, decreasing urine output) 3, 4
• Acute RVT presenting within 24-48 hours of symptom onset with impaired kidney function 3, 4
• Failure of anticoagulation alone with progressive renal dysfunction 4
• Bilateral RVT or RVT in a solitary kidney where renal salvage is critical 4

Technical Approach and Outcomes

• Mechanical thrombectomy can be performed alone or combined with catheter-directed thrombolysis (mean duration 22 hours in published series) 4
• Restoration of renal vein flow is achievable in nearly all cases, with mean serum creatinine improving from 3.3 mg/dL to 1.92 mg/dL post-procedure 4
• Glomerular filtration rate improves significantly (from 30.8 to 64.2 mL/min per 1.73 m²) 4
• Mechanical thromboaspiration systems (e.g., Penumbra Indigo) can achieve complete resolution without thrombolytic agents in select cases 5

Contraindications to Thrombolysis

• Active bleeding, recent intracranial hemorrhage, or brain metastases 1, 6
• Platelet count <50 × 10⁹/L (though full anticoagulation is appropriate with platelet count of 159 × 10⁹/L) 6
• Recent major surgery or trauma 6

Long-Term Anticoagulation

Transition Strategy

• Continue full-dose parenteral anticoagulation for at least 5-7 days 1, 6
• Overlap with warfarin (target INR 2-3) starting within 24 hours of initiating heparin 1
• Discontinue heparin only after INR >2.0 for at least 2 consecutive days 1

Duration of Therapy

• Minimum 3-6 months of anticoagulation for provoked RVT (e.g., oral contraceptive use, hypercoagulable state) 1
• Extended anticoagulation should be considered for unprovoked RVT or persistent risk factors 1
• In cancer-associated RVT, continue anticoagulation as long as active malignancy persists 1

Agent Selection for Long-Term Therapy

• Warfarin (INR 2-3) is standard 1
• Direct oral anticoagulants (rivaroxaban 15 mg twice daily for 21 days, then 20 mg once daily; or apixaban) are alternatives for non-cancer patients with normal renal function 1
• For cancer-associated RVT, LMWH at 75-80% of initial dose is superior to warfarin (9% vs 17% recurrence rate) 1

Monitoring Requirements

Acute Phase Monitoring

• aPTT every 6 hours initially until stable therapeutic range achieved, then daily 1, 6
• Once warfarin initiated, check INR daily until therapeutic for 2 consecutive days, then 2-3 times weekly 6
• Serial creatinine and urine output monitoring to assess renal function response 4
• Hemoglobin monitoring for bleeding complications 6

Common Pitfalls to Avoid

• Do not delay anticoagulation while awaiting definitive imaging if clinical suspicion is high and diagnostic results will be delayed >4 hours 1
• Avoid standard-dose LMWH in severe renal impairment (CrCl <30 mL/min) without anti-Xa monitoring due to 2-3 fold increased bleeding risk 2
• Do not use enoxaparin at standard doses in renal failure; reduce to 30 mg subcutaneously once daily for prophylaxis or use UFH instead 2
• Recognize that warfarin directly increases aPTT by approximately 20 seconds for each 1.0 increase in INR, potentially leading to inappropriate heparin dose reductions 7
• Consider underlying hypercoagulable states (protein S/C deficiency, Factor VIII elevation, oral contraceptives, malignancy) as these require extended anticoagulation 3, 8